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Sharks/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Suspenseful music plays while a shark raises it head out of water. The shark is knocked on its head and falls back into the water, over and over. Someone is playing whack-a-shark at an amusement park. Tim throws a ball and it lands in a fishbowl. TIM: Yes! Tim won a live goldfish. He's handed the fish in a plastic bag. TIM: Thank you, good sir. Check it out, Moby! I won a-- aaaugh! A robot, Moby, holding a large plastic bag with a hammerhead shark in it, stands next to Tim. TIM: Where did you get that? MOBY: Beep. Moby shows Tim he got the shark at a stand called "Win an Apex Predator" where you throw a ball into a bull's-eye inside of an open, toothy mouth to win a caged eagle, lion, crocodile or a caged snake. TIM: There's no way you're bringing that thing home. Tim reads from a typed letter. TIM: Dear Tim and Moby, Can you guys help me solve this riddle my dad told me? What animal has no bones but thousands of teeth? From, Eli. That's no riddle, Eli. Your dad is talking about— The shark breaks out of Moby's bag, jumps onto the boardwalk, jumps a few times on land, and then flops into the ocean. TIM: Sharks. MOBY: Beep. TIM: Yeah, that guy was pretty flexible. That's because sharks don't have rigid bones. Like rays and skates, they're cartilaginous fish. Their skeletons are made of flexible tissue called cartilage. An image shows sharks, rays, and skates swimming around at the Cartilaginous Fish Class Reunion. They have refreshments and drinks on a table and balloons to celebrate the reunion. TIM: The same stuff we have in our noses and ears. Moby, wearing diving gear, drops down into the water to join the reunion. The sharks, rays, and skates swim away. MOBY: Beep. TIM: Cartilage is sturdy and durable, but it's about half as dense as bone. It keeps sharks lightweight, so they can zip through the sea. Tim is on a boat. A shark's fin is seen zipping around in the water. TIM: Sharks also have a unique flotation system, a large liver filled with oil. The oil is lighter than water, which helps them float. An animation shows the shark swimming underwater. Its internal organs are shown, and an arrow points to its liver. MOBY: Beep. TIM: Unlike sharks, bony fish use gas-filled chambers to float. They adjust these swim bladders like balloons to move up and down. The fins of bony fish can also move in different directions. That lets them make tiny, delicate movements. A top and bottom animation shows the shark and a bony fish with its gas-filled chamber showin. The bony fish's movements are shown. TIM: Shark fins are way stiffer, so they can't hover or move backward. They can only go forward. The shark curves its body and goes after the bony fish. Moby, who is underwater, scrapes the metal glove he's wearing when he reaches out and touches the shark as it swims by him. MOBY: Beep. TIM: Oh, yeah, sharkskin is pretty rough stuff. It's made up of microscopic toothlike scales called denticles. An image shows the shark's denticles. TIM: As sharks swim, the denticles channel water from head to tail. An animation shows water being channeled around the swimming shark. TIM: Between that and their streamlined shape, sharks are built for speed. An animation shows two racing sharks at a start line. Moby fires off a gun, and the sharks start racing. TIM:Blue sharks and makos have been clocked at over forty miles per hour. MOBY: Beep. A blue shark and a mako swim past. Moby takes a picture of the racing sharks. TIM: Right, the teeth. An image shows the shark's teeth. TIM: Each species has its own distinct type. In some dogfish, the teeth are long and spikey for stabbing prey. An image shows a dogfish. TIM: On the massive whale shark, they're tiny and curved backwards. I guess you don't need big teeth when you're just sucking in plankton. An image shows a whale shark's teeth and then the whole whale shark. MOBY: Beep. TIM: Moby reaches down and picks up shark teeth. TIM: Yeah, shark teeth aren't rooted in sockets like ours. They grow like fingernails from the tissue in their jaws. In fact, they probably evolved from denticles on their skin. MOBY: Beep. TIM: Just like denticles, shark teeth are continually replaced. It's like a conveyor belt. When one tooth falls out, another moves forward. An animation shows how sharks teeth fall out and are replaced as a row moves forward. TIM: Some sharks go through as many as thirty thousand in their lifetime. An animation shows many shark teeth sinking down into water. TIM: But teeth aren't the only adaptation that keep sharks at the top of their food chains. MOBY: Beep. TIM: They can also sense electricity. Hundreds of thousands of electric receptors dot the skin on their heads. An animation shows the receptors on a shark's head. TIM: They pick up signals that muscles emit, like a beating heart or twitching fin. That helps sharks target their prey as they close in. MOBY: Beep. An animation illustrates the receptors analyzing what's around the shark and monitoring its own body. Then the animation splits to show the bony fish and its beating heart that the shark can sense. TIM: I know. It's like some sixth sense out of a superhero movie. Unfortunately, the ocean is filled with manmade signals. The receptors continue analyzing what is around the shark. TIM: What a shark senses as a tasty fish might actually be a boat, a buoy, or— The shark hones in on a target it senses and bites part of Moby's protective diving gear. TIM: Fortunately, they have other tricks up their sleeves. Moby tugs on his oxygen line to be pulled up out of the ocean. MOBY: Beep. TIM: You may have heard that sharks can smell a drop of blood from miles away. MOBY: Beep. Moby climbs up to the side of the boat. Tim drops bait into the ocean. TIM: That's an exaggeration but their noses are very sensitive. They can even tell which direction smells are coming from. Three shark fins appear in the ocean. TIM: And great whites have a special trick. They've learned to poke their noses out of the water. A great white shark pokes its head out of the water and sniffs a scent of nearby seals that are on an island. TIM: Because smell travels faster through the air. MOBY: Beep. TIM: That coloring is called countershading, and most sharks have it. Tim and Moby view the shark that has its head out of the water. TIM: From below, their bellies help them blend into the sunlight. From above, their backs merge with the darkness of the deep. Pretty helpful for sneaking up on prey. Top and bottom images show how the shark blends with the sea from looking up or down at it. MOBY: Beep. TIM: Attacks on people are actually extremely rare, Moby. Most times, it's a mistake, and the shark swims away after the first bite. We're nowhere near as tasty as seals and dolphins. The shark turns away from Tim and Moby and swims toward the seals. TIM: The fact is, sharks should be a lot more scared of us. MOBY: Beep. TIM: People kill over one hundred million sharks each year. Many are hunted just for their fins, which are a delicacy in some countries. An animation shows a waiter serving a shark fin in a bowl. TIM: Sharks don't have a lot of offspring, so their numbers are plummeting. An animation shows the shark population decreasing in the oceans on a world map. MOBY: Beep. TIM: Yeah, it kinda makes you feel bad for— Tim drops bait into the ocean, and a great white shark sticks its head out close to Tim. He sees the shark and steps back. TIM: We're gonna need a bigger boat. Category:BrainPOP Transcripts